Prime or zoom? LensRentals investigates

In the latest LensRentals blog post, Roger Cicala writes: 'I’m going to address something I see repeated online all the damn time that just sets my scientific teeth on edge: This zoom is just as good as a prime.'

What follows is a fascinating look in to the mind-numbing complexities not just of zoom lenses, but of optical bench testing in general. It is worth a read for many reasons, as it offers great insights in to gear selection and gear testing.

Comments

Most of us reading the article learned something. Even the really clever people must have an improved appreciation of what they are buying into with their money.Bottom line: Informed consumers make manufacturers strive to improve their products.

That was a really well written article. I'm a mechanical engineer and appreciate how difficult it is to write about complex concepts in clear and simple language without talking down to the audience. It's easy to throw around a lot of technical jargon and cause more confusion than understanding or come across as condescending.

I also do a lot of testing and appreciate that no two parts are ever exactly the same. Man has never made a round hole or a straight line or a flat surface. Those are just concepts that we try to approach with our manufacturing. So when you take a whole lot of imperfect objects and put them into complex assemblies there will inevitably be performance variation. Whole textbooks and careers have been build on controlling variation in complex assemblies.

Fortunately, for most of us and most things, we do not need perfection, just good enough at a reasonable cost.

"I also do a lot of testing and appreciate that no two parts are ever exactly the same. "Depends on the design & manufacturing tolerance and intent for interchangeability. Are you talking about tolerance of PLANK LENGTH?

Man has never made a round hole or a straight line or a flat surface.REALLY? What is your reference points and how did you measure?How FLAT and how smooth is the surfaces.

Excellent post. Makes one wonder if it would be possible to do statistical reviews "this is the bell curve of performance for this lens...". Although that sounds like it would take an absurd amount of time and money.

How many photographers actually require ultimate sharpness, perfect corners etc? I'd be willing to bet that number is much, much smaller than the number that moan/argue/discuss it online (and those that do need ultimate sharpness are probably too busy to be on a forum discussing it anyway).

If the convenience of a zoom 'gets you the shot' over a prime then it doesn't really matter how much sharper the prime was.

Yep. The guy who shoots young kids' sports at our YMCA (and surely has contracts at schools) uses a slow (F4 I think) zoom lens...and this was 8+ years ago, before sensors got so good. He compensated with multiple strobes/flashes. I took a few snapshots with my Rebel 450d and 30mm Sigma F1.4. Fast enough that I didn't need flash (and likely was at ISO 200 - that camera gets slightly noisy at ISO 400 and bad at 800).

Zooms make great wedding portrait lenses. Most brides need a little softening anyway. But generally the bokeh quality and field separation makes a bigger difference to my photographs than image sharpness. This is why I shoot with primes most of the time.

Thanks to Roger for an informative article. Intuitively, we all know (or should know) that zooms show more variability in performance, given their more complex optics. In the end, some are better than others, and statistics/classifications based on a sample of 1 are worthless.

choosing between zoom and prime is a combination of a lot of formulas :- Location : is it under control or not .- Subject : is it simple (portait) or complicated (as in weddings) .- Need for large f/x , bokeh , light ... .- need for AF speed .- perspectives .- and the most important : photographer's taste and style .

well, i think it's all in your last point: "photographer's taste ant style". You can cover a complicated thing as wedding with only a 24-70/2.8 or a 28-300/3.5-5.6L, or with two bodies with a 35 and an 85 ... or whatever your style is. I've seen results from the mentioned combos and all look good, and did great jobs. Just different styles.

kind of ... but things are more complicated in real life... a high quality zoom, say 24-70/2.8 would be comparable in quality to a pack of 24/35/50/85 about F2 average primes... also it's high price wouldn't seem that huge compared to a 4pack ... and so on and on :)

"Sigma circumvented that" :) not... sigma just produced a high quality zoom (as there are plenty of high quality zooms), they did not produce a zoom as good as a couple of high quality primes in that range can be.

Unless I can afford every prime single lens available for my cameras And Also the services of a lens Sherpa, I am going to use zooms. I've been in too many situations where I cannot back up or move forward, and it isn't practical or even possible to have a variety of lenses on my person. It is ridiculous and ignorant to state that every type of photographer should use primes only.

It is not 'mind-numbing numbers' but excessive ego and hubris that makes Mr. Cicala's difficult to read. The first three sentences of the roles of quantitative and qualitative sciences demonstrate a poor understanding of their respective roles in understanding what our eyes see. Example, Einstein played piano constantly while pondering the concepts that were revealed on his three papers in 1905 ('annus mirabilis') that changed the way society looks at the world. Use of rage-filled phrases like "setting my teeth on edge" are a wonderful way to fog an issue: no one really cares about Mr. Cicala's frustrations except perhaps the author himself.

@laurenceSvirchev... I enjoyed reading Mr. Cicala's article and I don't think he was being at all too critical. The piece was definitely not difficult to read. Mr. Cicala mentioning that something "sets his teeth on edge" probably doesn't lead most people to think he's actually fitting with rage over what people say in forums about lenses... even if what many say is irritating and worth an eyeroll...

The bottom line is that most photographers would probably gain more knowledge than irritation after reading the piece.

Mike... Mr. Cicala wrote: "My point simply is that zooms vary more than primes in general, and a given copy of a zoom will vary at different focal lengths."

Meaning that the complexity of zoom lenses simply mean that you're going to see more variance between copies.

"Can they still be very good? Absolutely. Can they be as good as the **best primes**? Nope. On the other hand, the best primes don’t zoom worth a damn."

Meaning a $700 zoom (at any focal length) isn't likely to best a $6000 prime. However... will you *readily* see the difference between a 300 f/4 prime shot at f/8 vs. a 200-400 lens shot at 300mm and f/8, after both files are processed and printed at 20"x30" or smaller? Absolutely not... and that's the point that many photographers realize. You also won't see a practical difference between a $1,600 300mm f/4 prime and a 300mm f/2.8 prime... both stopped down to f/8 or so most of the time.

Required reading, with so many good takeaways. DxO has tried to boil this down to a single number, which is as useful as Dick Clark's Rate-A-Record.

But the desire for convenience goes beyond zoom lenses. Who wants to look at lots of charts and then be forced to admit that lenses vary--or worse, that primes are better than zooms because, for one thing, there is less to go wrong.

I remember one of the major photographic retailers in the U.K., advertising that all their lenses were tested and supplied with the testing charts. The inference was that any bad copies had been returned to the manufacturer (to be sold elsewhere I guess).

A few years back, Imaging Resource and Diglloyd ran tests of similar lenses and indeed found discrepancies. Among 50mm primes, IR found clear winners and losers although the differences were small. Lloyd Chambers had found large differences in corner sharpness with both Canon and Nikon medium to tele zooms.

With film, fewer of us had the opportunity to look closely (as in pixel peeping) to notice as we can now.

Modern Photography used to have a line about getting friendly with your camera dealer so could swap lenses if you got a dog but in general, not much is said about this because all parties have a vested interest in the consumer buying and keeping.

At one time, Linhof and Sinar used to do their own inspections, and it's thought provoking when you find a Schneider or even a Zeiss lens with a Linhof engraving, suggesting that even a Geman Zeiss lens was subjected to a second round of tests after leaving the manufacturer.

John, also these "variance" became more visible with increase in resolution. You will see that only after the sensors passed the 16MPx or so these discussions became frequent online. Also Roger underlines in his comparison that he used 36MPx camera, but the differences will look smaller on a lower MPx sensor and worse on 50MPx one.

Very useful article as most of the major players in the industry probably employ todays state of the art manufacturing techniques for manufacturing these lenses. I'll think twice about owning/investing in zooms and give more consideration to primes than I have in the past.

I'd love to use exclusively primes for what I do, but that would be impractical, so, warts and all, I stick with the holy triumvirate. I'm happy to compromise a bit of sharpness for practicality. It all depends on what and how you shoot.

While being scientifically sound, this blog article does not address factors contributing to the image rendering other than sharpness. Take the same picture with 2/50 Zeiss Planar and Leica Summicron lenses at f/5.6, and images will look different, albeit equally sharp.

Not only bokeh, even though it is probably the most noticeable factor. Lens plasticity is also very important: the way it deals with very small details of different tonal and color contrast.Another factor is flare and ability to preserve details when shooting against the light.

LensRentsals never claims to do complete reviews. If you read their piece on third graders (https://www.lensrentals.com/blog/2016/08/my-third-grader-analogy-for-lens-reviews-and-testing/), they even poke fun of themselves (and just about everyone else) when it comes to testing. Roger and his team have never said that they were the be all and end all of lens testing. They merely have a unique opportunity: multiple copies of lenses and optical testing equipment. While other lens performance measures may not be present, I really appreciate the time and efforts they spend offering insight into lenses.

I agree that for an engineering tuned mind this sort of activity may be entertaining. However, when it comes to actual usefulness for applied photographic purposes, the use is rather limited, unfortunately.

Agreed, except for your closing word "unfortunately." Our community has both Artists and Engineers, and each posting enriches the discussion to one degree or another, but rarely balanced between the perspectives.

I stopped using zooms on Canon around 2008. I used nothing but primes for four years. I had to use a zoom with Nikon for a while, but then I started using Sigma Art primes (I tried several Nikon primes, but I was unimpressed), and I could stop using zooms again.

I have one zoom now: a Sigma 150-600mm. I use it exclusively to shoot animals at the zoo, and accept the limitations for that.

In the studio I use a 50mm and an 85mm. In 2008, I was using the 50mm f/1.2 and the 85mm f/1.2. Now I'm using the 50mm Sigma Art and the 85mm Sigma Art.

Anyone notice a common theme in all the lens testing done, where the problems are?"Decentering" especially with fast lenses with elements with steep curves. Maybe it's time for mfg's to work on the mounting of these lenses, to create something not so prone to allowing lens decentering? Compensating mountings, or using better materials that can allow for closer contact with the lenses but not allow binding (aluminum and glass have different coefficients of expansion) if temperatures change in use.

I disassembled cleaned and repaired a few lenses. They are very complex to keep down the size, everything is squeezed into an incredibly small space. Lens decentering comes from manufacturing. Brand new lenses can be also decentered. If you drop it, if it's not a block of reinforced steel, it will bend. When talking about tolerances, I'm talking less than 0.03mm differences between parts, that makes these differences when they are assembled together. Larger aperture lenses cost more because they need much more quality control than narrow aperture lenses, because at F1.4 any deviation from ideal is much more pronounced than on a F4 lens

Centering can take two forms, 1, where the lens element is decentred in the lens body and 2, where two lens elements that are cemented were glued together off-centre. The first one you might be able to fix, the second requires a new element. The more curved the lens elements, the worse decentering errors makes things.

Well, you can contribute to the phenomenon or dampen with each post. Several of the older members use the Brit term Horses For Courses, which is true. As an equipment forum, this is a community of widely different perspectives, attitudes, needs, backgrounds, etc. Posters are only human.

I find the Ignore button quite useful for dampening this effect, at least on my reading.

Great article. Puts the facts to the common knowledge that zooms can never be as good as a prime. I believe most know that, but acknowledges the usefulness and versatility of zooms, and from a image practicality standpoint, that beauty is in the eye of the beholder (which has nothing to do with the tech specs).

I would say it could apply to the 70-180/2.8 APO which is said to be slightly better than the 70-210/3.5 from Contax and very likely the 35-70/2.8 (they'd better have an excuse for the meager zoom range, large size and exorbitant price), but many other "Leica" zooms are actually Minoltas.

What a pointless article, only of intrest to those who can't sleep at night because they have been pixel peeping al day. Real photographers just get on with it and use what they want, not what they are told they should be using just because one man says he thinks they are eating.

"Some reviewer somewhere tested a single copy of a zoom lens and gave it their highest rating ever. Some people actually argued online about that, and then asked my opinion about that argument. So I wrote this post to explain why I thought it was all meaningless." - From the referenced article.

You know, the one a few didn't bother to read, which led them to make odd statements about pixel peeping and the like.

DxOMark isn't a review site. The primary purpose for their camera imaging system and lens measurements are for correction of image imperfections when the raw images are developed. The publishing of their measurement data is just a bit of fluff on the side, though the publicity must do them some good.

I like individual DxOMark measurements, but I ignore their overall scoring of camera imaging systems and lenses.

However lens variation calls into question how well the measured imperfections will work with your equipment. Centering, in particular, seems problematic.

@ Henry McA. Some of us have to use both prime and zoom lenses when we travel due to weight and size restrictions of carryon. Yes it maybe a compromise but is a logical means to an end to take a decent quality zoom lens along with us. Also thank goodness to all those "tourists and amateurs" out there loading and sharing their images from either prime or zoom glass. By the way Henry I can't see any images or gear you own online. Dare I say you might own a zoom and can't share the fact out of embarrassment.

Has anybody mentioned yet that if you need a 75 because with the 85 you can't get everything needed on the picture so you have to use your 50 you loose over half of the pixels of your sensors? Yes I know with the 50 you would only use the best part of the image but still, zooms have this advantage of pixel-use.

Usually people who say that have no clue that zooming with your feet is not a option. Besides, changing the distance to subject changes perspective, which means a different photo. With a zoom lens you can change the perspective in order to get the most suitable background for the best composition.

1. Don't rely on sites that test just one copy of a lens (that would be all sites except Lensrentals), especially if it is a zoom. Check at least three review sites. And check the user forums. 2. Zooms are extremely useful. Their usefulness easily outshines their imperfections. 3. Try to use prime more. Often we can do it if we are slightly less lazy. 4. If all you do is post in forums in small sizes or if you are not a sharpness/resolution warrior, you shouldn't worry about MTF charts. You should be more concerned other characteristics such as CA, vignetting etc. 5. You know better than anyone else what you should do.

They might not all be duds but quality control could be poor, resulting in lots of duds. And the sample sent for testing, if it comes directly from the distributor will certainly be good. Even then, they can label it "pre-production" in case it got bounced around in the FedEx truck.

No company on earth has 100% QC, and with humans involved in the pipeline mistakes will always be made. Not every lens that is produced is rigorously tested, it's a statistical sampling process, so poor lenses can always get through to the customer. It's the % that matter. I would only be worried by consistent reports of trouble with a lens and these days that's not a common thing.

photography is an art. you got perfect gear but situation won't happen to be perfect. everyone tend to make their available gear perfect as possible. sharpness at the whole frame? not really much important. you know what to shoot that you are focusing on.

yes.. but the one who got the first prize winner on landscape shootout, they may not using the perfect lens or gears or both combination at that time. it is from his technique mostly. they know what and when he should do to please people eyes.

While I used to prefer primes the Olympus 40-150mm Pro has forever changed my mind on the superior optics of what a zoom can be. Nocticron used to be my favorite lens all time until I bought the 40-150mm Pro 😁

42 is the "Answer to the Ultimate Question of Life, the Universe, and Everything" by the supercomputer named Deep Thought in Douglas Adams's novel Hitchhiker's Guide to the Galaxy and now by Roger Cicala. :)

I'm actually pretty surprised that our image quality from enormous hand-telescope of a device is actually so inconsistent. I know that there is variation in manufacturing, but it's so bad that typically nobody is going to know for sure of the quality they have.

I bet a person who made a camera body that did nothing but analyze a lens for the consumer would sell a lot of units. Just a readout on an LCD, it doesn't take pictures at all. There's a permanent test chart laser etched on the sensor. The readout tells the user to zoom out through the focal range and when to change the aperture; then you put the SD card in your computer and run the program and you get the results. A score of 72, not bad; I think I'll keep this one...

A scientific measurement is generally only of value if it comes with uncertainties, as expressed for instance through a standard deviation. Thus, an informative lens test has to derived from several tens of lenses, at a minimum. From a consumer perspective, since i cannot afford testing the lenses I purchase, the lower number of the reported measured should be used as a quality measure of the lens.

stupid question: why is the subject distance not an important parameter? e.g. nobody ever talks about a given prime being soft for close objects but sharp for far ones. why not? (sorry if this is basic optics)

It can be, although not very often. I think the bigger reason is testing equipment is at a set distance: Optical bench is at infinity, Imatest and DxO are close up, etc. So no one really checks a single lens at multiple focusing distances.

in reply to shademaster: I'm always concerned that wide-angles tested on DxO or Imatest are being tested too close (it can be 3-4 feet testing distance, but even 6 concerns me). On the other hand Macro lenses tested on the optical bench at infinity are not at their best either. For most lenses in the standard to telephoto range, though, I doubt it matters much.

You seem not to ever have had a bad copy. I had, several times. They were really very very bad and it has each time cost me months to find out because retailers didn't know a thing and import servicers just kept my lens on the shelf for three months and then sent it back being 'calibrated' when they weren't.Thanks to tech websites like Lensrentals and guys like Roger I now know what can happen and how to find out myself a tiny bit: put lens on tripod, make photo's at various apertures and check not only the center but the far corners too whether they are acceptable.

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